Steering apparatuses have been provided with various countermeasures for preventing shakiness, or looseness, between column members connected with each other. In particular with the steering apparatuses configured to adjust an operation position of a steering wheel in a frontward and rearward direction of a vehicle, preventing shakiness between a fixed column member, which is retained to the vehicle, and a movable column member, which is movably supported and connected to the fixed column member, is considered most important. As an example, JP2010-208588A, hereinafter referred to as Reference 1, discloses an apparatus for enhancing rigidity of connection between members that connect with each other and providing a structure further restricting vibration for preventing shakiness in a steering column. The structure for preventing shakiness in the steering column disclosed in Reference 1 is the structure for preventing shakiness between an outer tube and an inner tube of the steering column, the outer tube and the inner tube of the steering column that rotatably supports a steering shaft and slidably fit relative to each other. The apparatus disclosed in Reference 1 includes a multiple number of through-holes formed on the outer tube provided with a separation distance between the through-holes in an axial direction of the outer tube. The apparatus disclosed in Reference 1 also includes thrust members, each of which fits to a corresponding through-hole in a state to be movable in a depth direction of the through-hole configured to thrust the inner tube, push nuts, each of which resiliently engages with an inner peripheral surface of the through-hole and restricts a movement of the thrust member in the opposite direction of the depth direction of the through-hole, and a biasing member that biases the thrust member in a direction toward the inner tube.
JP2001-310741A, hereinafter referred to as Reference 2, discloses a telescopic steering apparatus that provides a smooth telescopic movement with a simple configuration without generating a rotational movement of a movable bracket relative to a fixed bracket during a telescopic movement. The telescopic steering apparatus disclosed in Reference 2 includes a fixed bracket configured to be fixed to a vehicle body, a fixed shaft rotatably supported to the fixed bracket, a movable bracket fitted to the fixed bracket such that the movable bracket is slidable in an axial direction, a movable shaft connected to the fixed shaft such that the movable shaft is movable relative to the fixed shaft and configured to rotate integrally with the fixed shaft, the movable shaft rotatably supported to the movable bracket, and a movement mechanism that moves the movable bracket and the movable shaft in the axial direction relative to the fixed bracket and the fixed shaft. In the telescopic steering apparatus disclosed in Reference 2, an external peripheral portion of the movable bracket fitted to the fixed bracket is provided with at least one flat surface portion, and a contact member provided with a flat surface end portion that comes in contact with the flat surface portion is retained to the fixed bracket.
The outer tube and the inner tube described in Reference 1 correspond to the aforementioned fixed column member and the aforementioned movable column member, respectively. The fixed bracket and the movable bracket described in Reference 2 correspond to the aforementioned fixed column member and the aforementioned movable column member, respectively. In Reference 2, the fixed bracket includes a steering column and a lower tube, and the movable bracket includes a telescopic tube and an upper tube. Each of the members corresponding to the fixed column member and the movable column member in each of Reference 1 and Reference 2 is a tubular member either forming an outer tube or an inner tube. In each of Reference 1 and Reference 2, a thrust member is provided such that the thrust member applies thrust on an inner tube through a through-hole formed on an outer tube in order to prevent shakiness between the inner tube and the outer tube. Components used in Reference 1 more specifically are push nuts and biasing members, for example a plate springs or coned disc springs. Components used in Reference 2 more specifically are coned disc springs, a spacer, a snap ring, and bushes.
More specifically, the fixed column member serving as an outer tube of the steering apparatus in Reference 1 is the outer tube formed in a tubular form. Similarly, the fixed column member serving as an outer tube of the steering apparatus in Reference 2 is the fixing bracket that includes the steering column and the lower tube, each of which is formed in a tubular form. In other words, each of the components that serves as the outer tube of the steering apparatus in Reference 1 and Reference 2 is a component formed in the tubular form. The outer tube of the steering apparatus formed in the tubular form results in restrictions for the structure that prevents shakiness between the fixed column member serving as an outer tube, and the movable column member serving as an inner tube, which leads to an increase in number of components. For example, in Reference 1, push nuts and a multiple number of coned disc springs are provided in addition to thrust members. In addition to the increase in number of components, thrust members and push nuts make an assembly process difficult. In Reference 2, in addition to a multiple number of coned disc springs, a snap ring for fixing the coned disc springs to the outer tube is provided. In addition to the increase in number of components, the assembly process becomes difficult. Hereinafter, for a convenience of describing a steering apparatus for a vehicle in this disclosure more clearly, a main housing is the term used for the component corresponding to the fixed column member, in order to avoid confusion.
A need thus exists for a steering apparatus for a vehicle, which is not susceptible to the drawback mentioned above.